1. Field of the Invention
The present invention relates generally to articulated equipment position control, and particularly to a system and method for DGPS-based positioning of an operative piece of equipment, such as a farm implement, which is pulled, pushed or carried by a motive piece of equipment, such as a tractor, by manipulation of a power-articulated connection therebetween.
2. Description of the Related Art
Various equipment systems include articulated components. For example, a common configuration involves a “motive” component, which supplies the motive force for pulling, pushing or carrying a “working” component through an articulated connection located therebetween. For example, tractors serve as motive components in agricultural and other operations. The working components can comprise various implements, which perform specific “working” functions.
Articulated connections can be provided between such components to accommodate relative movement therebetween. For example, detachable hitches allow the equipment systems to be reconfigured in various combinations, depending on the task at hand. Moreover, such articulated interconnections commonly accommodate relative movement between the components. Common examples in agricultural equipment systems include three-point hitches, clevis-type hitches, drawbars, etc. “Free” movement articulated connections include pivotal hitches. “Fixed” articulated connections include two-point and three-point hitches. Both types of articulated connections allow relative movement between the motive and working components. Such relative movement may be necessary to accommodate turning, as in the case of tractors pulling wheeled ground-working implements along curved travel paths, which are accommodated by pivotal hitches. Relative movement in the case of two-point and three-point hitches can involve adjusting implement height, pitch and other attitudes with respect to a tractor.
An example of articulated equipment with GPS-based guidance capabilities is shown in U.S. Pat. No. 6,539,303 for GPS Derived Swathing Guidance System, which is incorporated herein by reference. GPS guidance can utilize absolute positioning techniques based on GPS coordinates, or relative positioning based on previous travel paths and previously identified locations. Various error correction techniques are employed to improve the accuracy of GPS positioning. For example, Whitehead U.S. Pat. No. 6,397,147 for Relative GPS Positioning Using a Single GPS Receiver with Internally Generated Differential Correction Terms and U.S Pat. No. 6,469,663 for Method and System for GPS and WAAS Carrier Phase Measurements for Relative Positioning are assigned to CSI Wireless Inc. and are incorporated herein by reference. This technology is available from CSI Wireless Inc. under its trademark “e-Dif™”. The Global Navigation Satellite System (“GNSS”) currently includes GPS, the GLONASS (“GLObal NAvigation Satellite System”) satellites of the former USSR and other satellite ranging technologies. Current GNSS augmentation systems include WAAS (Wide Area Augmentation System) in the United States, EGNOS (European Geostationary Navigation Overlay System) in Europe and MSAS (Multifunctional Transport Satellite Space-based Augmentation System) in Japan. Each of these augmentation systems, which are all compatible, includes a ground network for observing the GPS constellation, and one or more geostationary satellites.
Relatively precise GPS positioning can be achieved with real time kinetic (“RTK”) technology. For example, U.S. Pat. No. 6,469,663 for Method and System for GPS and WAAS Carrier Phase Measurements for Relative Positioning discloses a single frequency RTK solution, and is incorporated herein by reference. Such greater precision can significantly expand the commercial applications for DGPS-based positioning and navigation. For example, in row crop agriculture, sub-meter tolerances are necessary to avoid equipment damage to crops. The application of DGPS-based automatic guidance offers the potential for reducing steering deviation associated with manual steering and guidance based on disk markers, foam markers and other prior art, non-automated techniques. However, guiding articulated agricultural equipment is particularly challenging because crop damage can be caused by either the motive or the working component, or both.
The present invention addresses this problem by providing a system and method for positioning a working component relative to a motive component by a power-articulation of the hitch or other connection therebetween. Heretofore there has not been available an articulated equipment position control system and method with the advantages and features of the present invention.
Other related art patents include: U.S. Pat. No. 6,434,462 for GPS Control of a Tractor-Towed Implement; U.S. Pat. Nos. 5,511,623 and 5,664,632 for Quick Hitch Guidance Device; and U.S. Pat. No. 5,725,230 for Self Steering Tandem Hitch.